ExH is in a new relationship (possibly weeks old - since mid to late August). The first DC are aware of since we split in 2017.
We have 2 DC, DC12 & DC10. They met New Girlfriend (NG) for the first time 2.5 weeks ago, no prep, just arrived with their dad at her flat, hung out, went to a fireworks display, back to the flat "until late" ("we watched YouTube, they weren't in the room with us") and then back to ExH home.
Second time was last weekend (bad timing we had to switch weekends so DC12 went twice in a row) - they (DC12 + ExH + NG) went out on a "date" for lunch. NG & XH were kissing, making DC12 v uncomfortable.
ExH lacks boundaries particularly with regards PDA (I had to be quite firm in early weeks and then all affection was removed when we married, so DC have never seen F display these sorts of behaviours.)
Is there anything I can do to help DC navigate this? NG has no DC, so is as awkward around DC as their F (he ain't a 'D'F he's quite cruel to them, trauma based childhood so childlike behaviours, emotional detachment, no interest shown in DC just tick boxing court ordered alternate weekends and 2 weeks max over school holidays), and together, they're proving a little difficult to manage.
DC12 is having a bit of a MH crisis currently (totally overwhelmed by a lot of things including possibility of nuclear war, cost of living crisis, Putin - you name it, they're exposed to it at F's house as news on full blast 24/7) and their anxiety is through the roof. Am using grounding techniques each evening to ensure DC doesn't spiral downwards (which they did during pandemic).
I'm concerned at how anxious DC are becoming about spending half Xmas hols with their F. DC10 keeps asking to count the days in my diary that they're supposed to be going, and is now asking me to reduce them (9 overnights).
AIBU to be concerned about all this or should I just keep reassuring DC? I'm a bit lost.